The U.S. Army appears as the only Allied Faction in the game. The player takes control of Sgt. Roland Roger of the 1st Infantry Division, 16th Mechanized Infantry Regiment, Fox Company. The player also takes control of the protagonist's brother, "Stretch" Roger of the USAAF. The U.S. Army also appears in the Multiplayer mode of the game.

The U.S. Army appears again in Call of Duty 3 as the first campaign once again. The player takes control of Pvt. Nichols from the 29th Infantry Division. The U.S. Army appears in the Multiplayer mode of this game like the previous installments

The U.S. Army is featured in Call of Duty: Modern Warfare 3, where the player takes on the role of a Delta Forceoperator and frequently encounters U.S. Army Rangers in Delta Force missions. U.S. Army Rangers are first seen in the beginning of "Black Tuesday", where they are fighting in New York with their Stryker. It is mentioned that the Army is fighting a losing battle due to a jamming tower preventing air support. After the destruction of the jamming tower by Delta Force Team Metal, the U.S. Air Force provide air support to the Infantry on the ground and succesfully drive the Russians out of Manhattan.

Delta Force is a playable faction in multiplayer, facing the Spetsnaz and Inner Circle in all their engagements.

Players also play using Delta Force first and third-person models in most Special Ops missions. A notable exception is Special Delivery, where the player uses a Modern Warfare 2 U.S. Army Ranger first and third person model instead.

In Survival Mode, the players always play as one or two Delta Force operators. The player(s) can call in additional Delta support via the Delta Squad reward, purchasable via the Air Support terminal. This ships three A.I. controlled Delta Force operatives armed with M16A4 rifles and Five-Seven sidearms.

CEO Jonathan Irons was once a trained U.S. Army soldier in the West Point Graduate Program. He left the Army later on and founded the Atlas Corporation. The Army is also seen fighting the Atlas Corporation in the Battle of New Baghdad.

"This is Bastogne... I studied it at the academy. I cited it in my final paper as one of greatest examples of courage and bravery in military history. One of those battles that show you what you're really made of, who you really are. I used to dream about it."

The World War 2 era U.S Army is an ally faction during the mission "Demon Within". In this mission, player using DNI to break into Sarah Hall's internal world where she reminisced about the Battle of Bastogne to cite for her final paper at the academy. The Player must fight against Hall's delusions of German Military. In Hall's internal world, German Military and US Military are both using 2060's era weapons.